linux-kernel - Re: [PATCH v2 8/8] block: Init for CBD(CXL Block Device) module

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Message-ID: <27bf8cff-83b6-4a41-923a-7713a847f979@infradead.org>
Date: Tue, 24 Sep 2024 09:35:18 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Dongsheng Yang <dongsheng.yang@...ux.dev>, axboe@...nel.dk,
 dan.j.williams@...el.com, gregory.price@...verge.com, John@...ves.net,
 Jonathan.Cameron@...wei.com, bbhushan2@...vell.com, chaitanyak@...dia.com
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-cxl@...r.kernel.org, linux-bcache@...r.kernel.org
Subject: Re: [PATCH v2 8/8] block: Init for CBD(CXL Block Device) module

Hi.

On 9/18/24 3:18 AM, Dongsheng Yang wrote:
> diff --git a/drivers/block/cbd/Kconfig b/drivers/block/cbd/Kconfig
> new file mode 100644
> index 000000000000..16ffcca058c5
> --- /dev/null
> +++ b/drivers/block/cbd/Kconfig
> @@ -0,0 +1,45 @@
> +config BLK_DEV_CBD
> +	tristate "CXL Block Device (Experimental)"
> +	depends on DEV_DAX && FS_DAX
> +	help
> +	  CBD allows you to register a persistent memory device as a CBD transport.
> +	  You can use this persistent memory as a data cache to improve your block
> +	  device performance. Additionally, if you enable CBD_MULTIHOST, cbd allows

s/cbd/CBD/ for consistency. Or does 'cbd' here explicitly refer to the loadable module
name?

> +	  you to access block devices on a remote host as if they were local disks.
> +
> +	  Select 'y' to build this module directly into the kernel.
> +	  Select 'm' to build this module as a loadable kernel module.
  +	  The module will be called cbd.

> +
> +	  If unsure say 'N'.
> +
> +config CBD_CRC
> +	bool "Enable CBD checksum"
> +	default N

We usually omit 'default N' since that is the default default.

> +	depends on BLK_DEV_CBD
> +	help
> +	  When CBD_CRC is enabled, all data sent by CBD will include
> +	  a checksum. This includes a data checksum, a submit entry checksum,
> +	  and a completion entry checksum. This ensures the integrity of the
> +	  data transmitted through the CXL memory device.
> +
> +config CBD_DEBUG
> +	bool "Enable CBD debug"
> +	default N

Ditto.

> +	depends on BLK_DEV_CBD
> +	help
> +	  When CBD_DEBUG is enabled, cbd module will print more messages
> +	  for debugging. But that will affact performance, so do not use it

	                               affect

> +	  in production case.
> +
> +config CBD_MULTIHOST
> +	bool "multi-hosts CXL Dlock Device"

	                      Block

> +	default N

drop default line.

> +	depends on BLK_DEV_CBD
> +	help
> +	  When CBD_MULTIHOST is enabled, cbd allows the use of a shared memory device

cbd or CBD?

> +	  as a cbd transport. In this mode, the blkdev and backends on different

ditto.

> +	  hosts can be connected through the shared memory device, enabling cross-node
> +	  disk access.
> +
> +	  IMPORTANT: This Require your shared memory device support Hardware-consistency

	                  requires                          supports

> +	  as CXL 3.0 described.

	  as described in CXL 3.0.